Android Studio Sync Project报错

通常是maven仓库不对，或者依赖库存在问题。
maven可以使用aliyun的：

buildscript {
    repositories {
        maven { url 'http://maven.aliyun.com/nexus/content/groups/public/' }
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.2'
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

依赖库问题需要检查dependencies里的依赖是否都能加载的到：

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
}